The quantification of pain can be effected by various techniques. For example, in U.S. Pat. Ser. No. 2,453,841, a pressure is applied to the human body until the subject indicates that pain is felt and then a neutralizing pressure is applied close to the original site of pain application to relieve the pain and the levels of applied pressure can be quantified until a reproducible indication of the sensitivity of the subject to pain is obtained.
In U.S. Pat. Ser. No. 4,641,661, the point of a probe is pressed against the skin and acts upon a transducer which measures applied pressure. The subject can operate a switch when the pain thus generated reaches a threshold value and a digital indicator can then record the pressure of the transducer which will represent the pressure level at which the pain threshold is reached for that individual.
Mechanical skin-sensitivity detectors are described in U.S. Pat. Ser. Nos. 1,637,421 and 2,704,539.
In general a variety of techniques have been utilized in the field of biofeedback and elsewhere to associate particular stimulus with a sensation to which the patient may be sensitive.
However, in spite of the developments in these fields to date, there has yet to be provided a device or method which can provide a quantitative indication to a third party, hereinafter referred to as an observer, of a state of being of a subject such that the state of being can be quantified effectively and reproducibly.